When it’s been a stressful day at work, it’s anyone’s guess how many cups of coffee have gone down the hatch.

A new app created by Jawbone called UP Coffee takes the guesswork out of how much caffeine you’re putting in your body and how it’s effecting your sleep cycle.

Exactly how does Up Coffee work?Users log their coffee intake by entering anything from a “small, hot Dunkin’ Donuts coffee” to “can of Diet Coke,” and the app figures out the amount of caffeine in the drink.

Based on the amount of caffeine you’ve logged, UP Coffee rates you on a scale from “Wired” to “Ready to Fall Asleep.”

The UP Coffee app works best when synced with Jawbone’s fitness band. Then, you can also sync your actual sleep data with the app, and analyze how your caffeine intake affects your sleep patterns overtime. You’ll get data like how much sleep you lose on average for every 100 mg of caffeine you take in.

Because each person metabolizes caffeine differently, UP Coffee is like your own personal sleep study.